Numerical predictions on fluid flow and heat transfer in U-shaped channel with the combination of ribs, dimples and protrusions under rotational effects
Numerical predictions on fluid flow and heat transfer in U-shaped channel with the combination of ribs, dimples and protrusions under rotational effects
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DOI：
10.1016/j.ijheatmasstransfer.2014.09.057
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发表时间：
2015
影响因子：
5.2
通讯作者：
Zhongyang Shen;Yonghui Xie;Di Zhang
中科院分区：
文献类型：
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作者：
Zhongyang Shen;Yonghui Xie;Di Zhang
近年来，由于其在压力损失方面的优势，凹坑和凸起结构被证明是一种有效的冷却剂通道强化传热方式。将肋、凹窝或凸起组合的复合强化传热技术应用于类似燃气涡轮机叶片内通道的U形方通道。考虑到燃气涡轮机叶片在运行时的旋转条件，为了更接近真实的运行条件，还研究了旋转对冷却剂通道的影响。因此，本研究旨在探讨旋转对涡轮机叶片类U形通道内流体流动与换热性能的影响，该通道为肋、凹窝或凸起的组合结构。研究的雷诺数为125万，考虑的旋转数包括0，0.4和0.6。根据计算结果，给出了非旋转和旋转两种情况下双通道复合强化传热结构的流场分布。同时，空间努塞尔分布粗糙的壁面，以揭示传热率。最后，面积平均努塞尔数比和通道摩擦损失进行了评估。结果表明，凸肋结构是最有效的结构，而凹肋结构的优势仅略大于凸肋通道。此外，凹坑和凸起结构的附加摩擦损失很小。可以预期，通过对凹坑/凸起结构的密集排列和形状优化设计，可以进一步提高该复合结构的热性能。
Recently, dimple and protrusion structure has been proved as an effective heat transfer augmentation approach on coolant channel due to its advantage on pressure penalty. A compound heat transfer enhancement technique, the combination of ribs, dimples or protrusions, is applied to a U-shaped square channel similar with the gas turbine blade internal passage. Considering the rotational condition of gas turbine blade on operation, the effect of rotation is also investigated for the coolant channel in order to approximate more to the real operation condition. Thus, the objective of this study is to discuss the effect of rotation on fluid flow and heat transfer performance of turbine blade similar U-shaped channel with the combination structure of ribs, dimples or protrusions. The investigated Reynolds number is 1.25 million and considered rotational number includes 0, 0.4 and 0.6. From the results, the fluid patterns of two-pass channel with compound heat transfer enhancement structure are presented for none-rotating and rotating cases. Meanwhile, spatially Nusselt distributions of roughened walls are obtained to reveal the heat transfer rates. Finally, the area averaged Nusselt number ratio and channel friction penalty are evaluated. The results indicate that rib-protrusion structure seems to be the most effective structure while rib-dimple structure has only slight advantage than ribbed channel. Furthermore, the additional friction penalty by dimple and protrusion structure is tiny. It can also be expected that, the thermal performance of this compound structure can be even improved after a denser arrangement of dimple/protrusion structure and optimal shape design.